McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 201. |
The general gas equation is |
| A. | PVn = constant |
| B. | PV = (RT)m |
| C. | PV = constant |
| D. | PV = mRT |
| E. | PV = RT |
| Answer» D. PV = mRT | |
| 202. |
Heat is transferred from an insulated steam pipe to the surrounding still air by |
| A. | Conduction |
| B. | Radiation |
| C. | All the above together |
| D. | Forced convection |
| E. | Free convection |
| Answer» E. Free convection | |
| 203. |
Three Carnot engines A, B and C having source temperature of 750?K, 700?K and 650?K have sink temperatures respectively 400?k, 350?k and 300?k. Which engine is the least efficient? |
| A. | All being Carnot engine have identical efficiencies |
| B. | Pulsejet |
| C. | Engine B |
| D. | Engine C |
| E. | Engine A |
| Answer» E. Engine A | |
| 204. |
The energy required to heat 1 gm of water from 0?F to 0?C will be nearly |
| A. | 32 cal |
| B. | 74.6 J |
| C. | Pulsejet |
| D. | zero |
| E. | 32 J |
| Answer» B. 74.6 J | |
| 205. |
For a gas the difference between the values of Cp and Cv aceounts for |
| A. | external work done |
| B. | increased kinetic energy of molecules |
| C. | increase in volume is more rapid as compared to that of pressure |
| D. | None of the above |
| E. | Pulsejet |
| Answer» A. external work done | |
| 206. |
The critical pressure at which latent heat of vaporisation for water is zero is |
| A. | 250.6 kg/cm2 |
| B. | 100 kg/cm2 |
| C. | 228.6 kg/cm2 |
| D. | 235.6 kg/cm2 |
| E. | 215.1 kg/cm2 |
| Answer» C. 228.6 kg/cm2 | |
| 207. |
Brayton cycles processes are |
| A. | Two isothermals constant volume a constant pressure |
| B. | One constant pressure, one constant volume, two adiabatics |
| C. | Two isentropics and two constant pressure |
| D. | Two isothermals and two isentropics |
| E. | Two isentropics and two constant volume |
| Answer» C. Two isentropics and two constant pressure | |
| 208. |
A gas which obeys kinetic theory perfectly is known as |
| A. | Diatomic gas |
| B. | Monoatomic gas |
| C. | Perfect gas |
| D. | Pure gas |
| E. | Real gas |
| Answer» C. Perfect gas | |
| 209. |
In an automobile the gear box is fitted between |
| A. | Differential and wheels |
| B. | Engine and clutch |
| C. | Engine and flywheels |
| D. | Clutch and wheels |
| E. | Clutch and differential |
| Answer» E. Clutch and differential | |
| 210. |
In an isothermal process |
| A. | Pressure remains constant |
| B. | Inter-molecular energy remain constant |
| C. | Temperature remains constant |
| D. | Kinetic energy remains constant |
| E. | Volume remains constant |
| Answer» C. Temperature remains constant | |
| 211. |
Which of the following gas has the highest values for the adiabatic index? |
| A. | Air |
| B. | Helium |
| C. | Methane |
| D. | Oxygen |
| E. | Nitrogen |
| Answer» B. Helium | |
| 212. |
The mixing process of two fluids is always considered as |
| A. | reversible or irreversible depending upon the gases involved |
| B. | Pulsejet |
| D. | reversible |
| E. | irreversible |
| Answer» E. irreversible | |
| 213. |
In which of the following energy conversion takes place at ambient temperature? |
| A. | Solar radiation |
| B. | Pulsejet |
| C. | Thermionic generator |
| D. | Magnetohydrodynamic conversion |
| E. | Battery producing electrical energy |
| Answer» E. Battery producing electrical energy | |
| 214. |
If the sun becomes twice as hot |
| A. | its output of radiation energy will fall |
| B. | it will radiate predominantly in infra-red |
| C. | it will disintegrate into fragments |
| D. | Pulsejet |
| E. | it will radiate predominantly ultraviolet |
| Answer» E. it will radiate predominantly ultraviolet | |
| 215. |
On a temperature-entropy diagram the slope of constant pressure line is given by |
| A. | S/T |
| B. | Cv/T |
| C. | T/Cp |
| D. | T/Cv |
| E. | T/S |
| Answer» C. T/Cp | |
| 216. |
Planck's law of radiation is applicable to |
| A. | Radiation of any kind |
| B. | Temperature radiation |
| C. | Monochromatic radiation |
| D. | Thermal radiation |
| E. | None of the above |
| Answer» E. None of the above | |
| 217. |
Identify the correct statement |
| A. | Thermal conductivity is independent of temperature |
| B. | Thermal conductivity increases with time |
| C. | Thermal conductivity varies with temperature |
| D. | Thermal conductivity increases with molecular weight |
| E. | Thermal conductivity increases as the rate of heat flow increases |
| Answer» C. Thermal conductivity varies with temperature | |
| 218. |
In a closed system, the change in enthalpy will be equal to the heat transferred when a reversible process takes place at constant |
| A. | Pressure |
| B. | Volume |
| C. | Entropy |
| D. | Temperature |
| E. | Internal energy |
| Answer» A. Pressure | |
| 219. |
The adiabatic horse power required to deliver 4 cu. M per minute of free air from 1 ata and 15?C to a received pressure at 7 ata would be in the range |
| A. | 20 ? 25 |
| B. | 5 ? 7 |
| C. | 7 ? 10 |
| D. | 15 ? 20 |
| E. | 10 ? 15 |
| Answer» A. 20 ? 25 | |
| 220. |
If a closed circuit is made of two dissimilar metals, an electric current flows in the circuit whdn the two junctions are maintained at different temperatures. This phenomenon is known as |
| A. | Seeback effect |
| B. | Peltier effect |
| C. | Maxwell's effect |
| D. | Faraday's effect |
| E. | Thomson effect |
| Answer» A. Seeback effect | |
| 221. |
Thermal efficiency of most of the internal combustion engines lies in the range |
| A. | 50 to 75 percent |
| B. | 90 to 100 percent |
| C. | 20 to 35 percent |
| D. | 75 to 90 percent |
| E. | 35 to 50 percent |
| Answer» C. 20 to 35 percent | |
| 222. |
A body of weight 100 N falls freely through a distance of 10 m against an atmospheric drag force of 5 N. Considering the body as the system, the work interaction is |
| A. | 250 Nm |
| B. | 1050 Nm |
| C. | 1000 Nm |
| D. | Pulsejet |
| E. | 50 Nm |
| Answer» E. 50 Nm | |
| 223. |
One bar pressure is the same as |
| A. | 1000 N/m2 |
| B. | 100 N/m2 |
| C. | 100,000 N/m2 |
| D. | 1 N/m2 |
| E. | 1000,000 N/m2 |
| Answer» C. 100,000 N/m2 | |
| 224. |
When a gas expands in a closed vessel, the maximum work will be done when the process is at constant |
| A. | Pressure |
| B. | Enthalpy |
| C. | Volume |
| D. | Entropy |
| E. | Temperature |
| Answer» A. Pressure | |
| 225. |
The RMS velocity of hydrogen gas at N.T.P. is nearly |
| A. | 4839 m/s |
| B. | 839 m/s |
| C. | 1839 m/s |
| D. | 2839 m/s |
| E. | 3839 m/s |
| Answer» C. 1839 m/s | |
| 226. |
The efficiency of a Rankine cycle may be expected to |
| A. | Increase with decreasing temperature of heat rejection |
| B. | Decrease with decreasing temperature of heat rejection |
| C. | Decrease with increasing temperature of heat rejection |
| D. | Increase with increasing exhaust pressure |
| E. | None of the above |
| Answer» A. Increase with decreasing temperature of heat rejection | |
| 227. |
A heat engine works on a Carnot cycle with a heat sink at a temperature of 27?C. The efficiency of the engine is 10%, the temperature of the heat source is |
| A. | 30?C |
| B. | 270?C |
| C. | Temperature shows the extent of expansion |
| D. | 60?C |
| E. | 10?C |
| Answer» D. 60?C | |
| 228. |
All of the following cycles consist of two isentropic processes EXCEPT |
| A. | Otto cycle |
| B. | Stirling cycle |
| C. | Pulsejet |
| D. | Carnot cycle |
| E. | Diesel cycle |
| Answer» B. Stirling cycle | |
| 229. |
1 micron is equivalent to |
| A. | 10-2 cm |
| B. | 10-3 cm |
| C. | 10-4 cm |
| D. | 10-6 cm |
| E. | None of the above |
| Answer» C. 10-4 cm | |
| 230. |
A system consisting of more than one phase is known as |
| A. | Isolated system |
| B. | Closed system |
| C. | Non-uniform system |
| D. | Open system |
| E. | Heterogeneous system |
| Answer» E. Heterogeneous system | |
| 231. |
In which case the work done per kg of air compressed from 1.05 ata, 15?C to 6.3 ata is minimum |
| A. | Polytropic with index n = 1.35 |
| B. | Adiabatic |
| C. | Polytropic with index n = 1.40 |
| D. | Isothermal |
| E. | Polytropic with index n = 1.3 |
| Answer» D. Isothermal | |
| 232. |
Thermei is |
| A. | A semi-conductor |
| B. | An impurity added to a semi-conductor |
| C. | A unit of temperature measurement |
| D. | A unit of latent heat |
| E. | Quantity of heat required to raise temperature of one tonne of water from 14.5?C to 15.5?C |
| Answer» E. Quantity of heat required to raise temperature of one tonne of water from 14.5?C to 15.5?C | |
| 233. |
"Heat flows from hot substance to cold substance unaided". The name associated with the above statement is |
| A. | Gay Lussac |
| B. | Joule |
| C. | Clausius |
| D. | Planck |
| E. | Kelvin |
| Answer» C. Clausius | |
| 234. |
The concept of black body in heat transfers applies to |
| A. | microns |
| B. | Objects which are black in colour |
| C. | Objects well insulated from surroundings |
| D. | Objects which are good conductors of heat |
| E. | Objects that completely absorb impinging radiation |
| Answer» E. Objects that completely absorb impinging radiation | |
| 235. |
A solar cell system is to suppmy 1050 kWh/month. The average output is 15 percent of the rated power. The rated power must be |
| A. | 4.5 kW |
| B. | Pulsejet |
| C. | 9.7 kW |
| D. | 3 kW |
| E. | 14.4 kW |
| Answer» C. 9.7 kW | |
| 236. |
Most of gases exhibit drop in temperature upon expansion. However, this may not be true in case of |
| A. | Carbondioxide |
| B. | Hydrogen |
| C. | Helium |
| D. | Oxygen |
| E. | Pulsejet |
| Answer» B. Hydrogen | |
| 237. |
The extension and compression of a helical spring is an example of |
| A. | Reversible process |
| B. | Adiabatic process |
| C. | Thermodynamic cycle |
| D. | Irreversible process |
| E. | Isothermal process |
| Answer» A. Reversible process | |
| 238. |
In a Carnot cycle if isothermal compression process is continued bit longer than the normal, then the adiabatic compression will cause the steam to arrive at the inner dead center at a temperature |
| A. | higher than the normal temperature |
| B. | lower than the normal temperature |
| D. | which is the normal temperature |
| E. | Pulsejet |
| Answer» B. lower than the normal temperature | |
| 239. |
Which of the following cycle consists of two constant pressure and two adiabatic processes? |
| A. | Carnot cycle |
| B. | Joule cycle |
| C. | Diesel cycle |
| D. | Dual cycle |
| E. | Otto cycle |
| Answer» B. Joule cycle | |
| 240. |
One litre of gas A and two litres of gas B. both having same temperature 100?C and same pressure 2.5 bar will have the ratio of kinetic energies of their molecules as |
| A. | 1 ; 2 |
| B. | 4 ; 1 |
| C. | 1 ; 1 |
| D. | 1 ; 4 |
| E. | Pulsejet |
| Answer» C. 1 ; 1 | |
| 241. |
Diesel cycle processes are |
| A. | Two isentropic, one constant volume one constant pressure |
| B. | Isentropic, isothermal, constant volume, constant pressure |
| C. | Two constant volume, one constant pressure, one isothermal |
| D. | Two isentropic and two isothermal |
| E. | Two constant pressure, one constant volume, one isentropic |
| Answer» A. Two isentropic, one constant volume one constant pressure | |
| 242. |
Which of the following cycle is less efficient than the remaining? |
| A. | Ericsson cycle |
| B. | Stirling cycle |
| C. | Otto cycle |
| D. | Pulsejet |
| E. | Carnot cycle |
| Answer» C. Otto cycle | |
| 243. |
The function of a clutch in automobiles |
| A. | To disengage power from engine to flywheel |
| B. | To disengage power from engine to gear box |
| C. | To disengage power from engine to wheels |
| D. | To absorb power |
| E. | To disengage power from wheels to engine |
| Answer» B. To disengage power from engine to gear box | |
| 244. |
The rate of heat flow from a 50 mm thick wall of material having thermal conductivity of 40 W/m?C for a temperature difference of 10?C will be |
| A. | 80000 kcal/m2 hr |
| B. | 800 kcal/m2 hr |
| C. | 2000 kcal/m2 hr |
| D. | 8000 kcal/m2 hr |
| E. | 80 kcal/m2 hr |
| Answer» A. 80000 kcal/m2 hr | |
| 245. |
According to the Kinetic theory of gases the collision between the molecules are assumed to be |
| A. | Perfectly elastic |
| B. | Partly elastic |
| C. | Partly inelastic |
| D. | 50% elastic |
| E. | Perfectly inelastic |
| Answer» A. Perfectly elastic | |
| 246. |
An isolated system |
| A. | Is a specified regon where transfers of energy and/or mass takes place |
| B. | Is a region of constant mass and only energy is allowed to cross the boundaries |
| C. | Cannot transfer either energy or mass to or from the surroundings |
| D. | Is one in which mass within the system is not necessarily constant |
| E. | None of the above |
| Answer» C. Cannot transfer either energy or mass to or from the surroundings | |
| 247. |
If during a process, the entropy of the isolated system increases, the process is |
| A. | Adiabatic |
| B. | Irreversible |
| C. | Reversible |
| D. | Ideal |
| E. | Isothermal |
| Answer» B. Irreversible | |
| 248. |
A constant volume gas thermometer closely follows |
| A. | Boyle's law |
| B. | Charle's law |
| C. | Gay Lussac's law |
| D. | None of the above |
| E. | Pulsejet |
| Answer» B. Charle's law | |
| 249. |
In a thermal power plant thermodynamic cycle used is |
| A. | Joule |
| B. | Brayton |
| C. | Carnot |
| D. | Erricson |
| E. | Rankine |
| Answer» E. Rankine | |
| 250. |
According to Boyle's law PV = C when the temperature is constant. In this relation the magnitude of C depends upon |
| A. | Pulsejet |
| B. | atmospheric pressure |
| C. | atomicity of the gas |
| D. | quantity of the gas involved |
| E. | molecular weight of the gas |
| Answer» D. quantity of the gas involved | |
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